WO2021066251A1 - Transition metal phosphide water-splitting catalyst, and method for producing same - Google Patents

Abstract

The present invention relates to a transition metal phosphide water-splitting catalyst and a method for producing same, and more specifically, to a transition metal phosphide water-splitting catalyst having excellent water-splitting activity, and a method for producing same.

Description

Transition metal phosphide water decomposition catalyst and preparation method thereof

The present invention relates to a transition metal phosphide water decomposition catalyst and a method for preparing the same, and more particularly, to a transition metal phosphide water decomposition catalyst having excellent water decomposition activity, and a method for preparing the same.

Research on electrochemical water decomposition catalysts that not only have low overvoltage and high current density, but also ensure stability in long-term use, have low cost, and excellent activity efficiency, are being conducted. IrO ₂ /RuO ^2- electrochemical water Decomposition catalysts and Pt-based electrochemical water decomposition catalysts are mainly being developed.

However, the IrO ₂ /RuO ^2- electrochemical water decomposition catalyst and the Pt-based electrochemical water decomposition catalyst are not only expensive, but also cause unintended side effects, so there are limitations in large-scale use.

Recently, studies of transition metal-based electrochemical water decomposition catalysts are being conducted, and in particular, interest in electrochemical water decomposition catalysts in which transition metals and phosphides exhibiting excellent activity efficiency are combined is emerging.

However, there is no development of a catalyst capable of satisfying both practicality and durability as an electrochemical water decomposition catalyst in which a transition metal and a phosphide are combined.

An object of the present invention is to provide a catalyst for water decomposition of a transition metal phosphide having excellent activity against water decomposition as well as inexpensive manufacturing cost and a method for producing the same.

In order to solve the above-described problems, the method of preparing the catalyst for water decomposition of a transition metal phosphide of the present invention proceeds with a hydrothermal synthesis process, and is prepared in an aqueous solution containing _{glucose (C 6} H ₁₂ O _{6 ).} 1st step of preparing an intermediate, ^{mixing a Ni 2+} precursor, a Co ²⁺ precursor, and urea in the first intermediate, and performing a hydrothermal synthesis process to prepare a second intermediate. Step 2, the third step of preparing a third intermediate by performing an oxidation reaction of the second intermediate, and a mixture and substitution reaction of _{sodium hypophosphite (NaH 2} PO _{2) to the third intermediate to decompose transition metal phosphides} It may include a fourth step of preparing the catalyst.

In a preferred embodiment of the present invention, the Ni ²⁺ precursor may include nickel nitrate (Ni(NO ₃ ) ₂ ).

In a preferred embodiment of the present invention, the Co2+ precursor may include cobalt nitrate (Co(NO ₃ ) ₂ ).

In a preferred embodiment of the present invention, the hydrothermal synthesis reaction in the first step may be performed at a temperature of 170 to 210° C. for 5 to 9 hours.

In a preferred embodiment of the present invention, the hydrothermal synthesis reaction of the second step may be performed at a temperature of 100 to 140° C. for 4 to 8 hours.

In a preferred embodiment of the present invention, in the second step, 225 to 275 parts by weight of the ^{Ni 2+} precursor and 450 to 1050 parts by weight of the ^{Co 2+ precursor may be mixed with respect to 100 parts by weight of the first intermediate.}

In a preferred embodiment of the present invention, the oxidation reaction in the third step may be performed for 2 to 4 hours at a rate of 2 to 4°C/min and a temperature of 260 to 340°C in an argon (Ar) atmosphere.

In a preferred embodiment of the present invention, the substitution reaction of the fourth step may be performed for 2 to 4 hours at a rate of 2 to 4°C/min and a temperature of 260 to 340°C in an argon (Ar) atmosphere.

In a preferred embodiment of the present invention, the transition metal phosphide water decomposition catalyst may have a BET (Brunauer-Emmett-Teller) specific surface area of ^{50 to 70 m 2} g ^-1.

In a preferred embodiment of the present invention, the first intermediate may be a micro-carbon sphere having an average size of 1 μm or less.

In a preferred embodiment of the present invention, the second intermediate may be a micro carbon sphere in which nickel-cobalt-hydroxide (Ni-Co-OH) nanoneedles are formed in a direction perpendicular to the surface.

In a preferred embodiment of the present invention, the third intermediate may be a micro carbon sphere in which nickel-cobalt-oxide (Ni-Co-O) nanoneedles are formed in a direction perpendicular to the surface.

In a preferred embodiment of the present invention, the fourth intermediate is a micro carbon sphere in which porous nickel-cobalt-phosphide (Ni-Co-P) nanoneedles having an average diameter of 30 to 70 nm in a direction perpendicular to the surface are formed. I can.

Meanwhile, the transition metal phosphide water decomposition catalyst of the present invention is a micro-carbon sphere and a porous nickel-cobalt-phosphide (Ni-Co-P) nanoneedle formed in a vertical direction on the surface of the micro-carbon sphere. It may include.

In a preferred embodiment of the present invention, the micro carbon sphere may have an average size of 1 μm or less.

In a preferred embodiment of the present invention, the porous nickel-cobalt-phosphide nanoneedle may have an average diameter of 30 to 70 nm.

In a preferred embodiment of the present invention, the transition metal phosphide water decomposition catalyst comprises 8.05 to 10.05 mol% of nickel (Ni), 25.91 to 27.91 mol% of cobalt (Co), and 25.66 to 27.66 of phosphorus (P) based on the total mol% of the transition metal phosphide. It may contain mol%, oxygen (O) 23.86 ~ 25.86 mol%, and carbon (C) 11.52 ~ 13.52 mol%.

In the present invention, the transition metal phosphide water decomposition catalyst and its preparation method have low overpotential values by improving both hydrogen generation reaction (HER) and oxygen generation reaction (OER), and are excellent in water decomposition activity.

1 is a diagram showing a schematic illustration of a method of manufacturing a transition metal phosphide water decomposition catalyst of the present invention in a preferred embodiment of the present invention.

2 is an FE-SEM image measured with a field-emission scanning electron microscopy (FE-SEM), (b) is an image of the first intermediate of the present invention measured at a magnification of 1 μm, ( c) to (d) are images of the second intermediate of the present invention measured at each magnification, and (e) to (f) are images of the transition metal phosphide water decomposition catalyst of the present invention measured at each magnification.

3A and 3B are TEM images of the transition metal phosphide water decomposition catalyst prepared in Example 1 measured at respective magnifications, and FIGS. 3C to 3E are prepared in Example 1 It is an HR-TEM image measured at each magnification of the transition metal phosphide water decomposition catalyst, and Figs. 3 (f) to (j) show the nanoneedles of the transition metal water decomposition catalyst prepared in Example 1 using an energy dispersion spectrometer ( EDS) shows the element mapping measured through, and FIG. 3(k) shows the EDAX spectrum quantitatively analyzed for the measured values of FIG. 3(f) to (j).

4A and 4B show the transition metal phosphide water decomposition catalyst prepared in Example 1, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1, and the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2, respectively. Is a graph showing the XRD pattern of, and FIG. 4(c) is a water decomposition catalyst of a transition metal phosphide prepared in Example 1, a second intermediate prepared in Example 1, and a water decomposition catalyst of a transition metal phosphide prepared in Comparative Example 1 And an X-ray photoelectron spectroscopy (XPS) measurement graph of each of the transition metal phosphide water decomposition catalysts prepared in Comparative Example 2, and FIG. 4(d) is the transition metal phosphide water prepared in Example 1. The high-resolution XPS spectrum of the decomposition catalyst Ni2p, FIG. 4E is a high-resolution XPS spectrum of the transition metal phosphide water decomposition catalyst Co2p prepared in Example 1, and FIG. 4F is A graph showing a high-resolution XPS spectrum of the transition metal phosphide water decomposition catalyst P2p prepared in Example 1.

5A shows the transition metal phosphide water decomposition catalyst prepared in Example 1, the second intermediate prepared in Example 1, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1, and the transition prepared in Comparative Example 2. It is a graph showing the adsorption-desorption isotherms of each of the metal phosphide water decomposition catalysts, and FIG. 5(d) is the transition metal phosphide water decomposition catalyst prepared in Example 1, the second intermediate prepared in Example 1, and Comparative Example 1. It is a graph showing the pore volume versus pore size distribution curves of the prepared transition metal phosphide water decomposition catalyst and the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2.

Figure 6 is a mixture of 10% by weight of platinum, the transition metal phosphide water decomposition catalyst prepared in Example 1, the transition metal phosphide water decomposition catalyst prepared in Example 2, the transition metal phosphide water decomposition prepared in Example 3 Hydrogen generation of the catalyst, the second intermediate prepared in Example 1, the third intermediate prepared in Example 1, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1, and the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2 As a diagram showing the reaction (HER; hydrogen evolution reaction) performance, (a) to (c) of FIG. 6 show ^{a scan rate of 10 mVs -1} and a linear sweep voltammetry (LSV) in 0.1M KOH electrolyte. The measured graph, Figure 6 (d) is a graph showing Tafel slopes, Figure 6 (e) is 0.86 ~ 0.96 V potential range (potential range), 2 ~ 25 mVs ^-1 scan speed Is a graph measuring the capacitive current density (capacitive J) in FIG. 6(f) is a chronocurrent method of the transition metal phosphide water decomposition catalyst prepared in Example 1 at current densities ^{of 10mAcm -2} and 100mAcm ^-2 This is a graph measuring chronoamperometric stability.

Figure 7 is a mixture of 10% by weight of ruthenium oxide (RuO ₂ ) carbon, a transition metal phosphide water decomposition catalyst prepared in Example 1, a transition metal phosphide water decomposition catalyst prepared in Example 2, prepared in Example 3 Transition metal phosphide water decomposition catalyst, the second intermediate prepared in Example 1, the third intermediate prepared in Example 1, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1, and the transition metal phosphide water prepared in Comparative Example 2 As a diagram showing the oxygen evolution reaction (OER; Oxygen Evolution Reaction) performance of each of the decomposition catalysts, Figures 7 (a) to (c) are linear in 0.1M KOH electrolyte saturated with nitrogen gas and a scan rate ^{of 10 mVs -1.} It is a graph measuring the scanning potential method (Linear sweep voltammetry, LSV), Figure 7 (d) is a graph showing Tafel slopes, Figure 7 (e) is a frequency range ^{of 10 5} ~ 10 ^-2 When a potential of -0.4V is applied at, an electrochemical impedance spectroscopy (EIS) is measured, and FIG. 7(f) is to confirm the stability of the transition metal phosphide water decomposition catalyst prepared in Example 1. , 1 This is a graph measuring the overpotential required to maintain the ^{cathode current density at 10mAcm -2} in the cycling process and the 1000 cycling process.

FIG. 8A is a view showing an electrolyzer system of Preparation Example 1 prepared using the transition metal phosphide water decomposition catalyst prepared in Example 1, and FIG. 8B is a view showing the electrolyzer system of Preparation Example 1 It is a graph showing the results of the linear periphery of each of the electrolyzer system and the electrolyzer system of Comparative Preparation Example 1, and FIG. 8(c) shows the overall water decomposition at a current density ^{of 50mAcm -2 with the catalyst described in the present invention and the previous paper} It is a graph showing the battery performance, and (d) of FIG. 8 shows the stability of the electrolyzer system of Preparation Example 1 and the electrolyzer system of Comparative Preparation Example 1 during water-splitting at a current density of ^{50 mAcm -2.} 8(e) is a transition metal phosphide prepared in Example 1 used as a cathode and an anode after decomposing water for 38 hours in the electrolyzer system of Preparation Example 1 at ^{a current density of 50 mAcm -2} It is an FE-SEM image obtained by measuring the water decomposition catalyst at a magnification of 200 nm.FIG. 8(f) shows the electrolyzer system of Preparation Example 1 ^{after water decomposition at a current density of 50 mAcm -2} for 38 hours, and then the cathode and the anode It shows elemental mapping of the transition metal phosphide water decomposition catalyst prepared in Example 1 used as an energy dispersion spectrometer (EDS).

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein. The same reference numerals are added to the same or similar elements throughout the specification.

The method for preparing the transition metal phosphide water decomposition catalyst of the present invention includes first to fourth steps.

Referring to FIG. 1, first, the first step of the method for preparing the transition metal water decomposition catalyst of the present invention is to proceed with a hydrothermal synthesis process, thereby preparing glucose (C ₆ H ₁₂ O ₆ ). It is possible to prepare a first intermediate (indicated by CS in FIG. 1) from an aqueous solution containing.

The hydrothermal synthesis reaction is one of the liquid phase synthesis methods, and refers to a reaction of synthesizing a substance using water or an aqueous solution under high temperature and high pressure, and the first intermediate prepared in the first step may be prepared from glucose.

In addition, the hydrothermal synthesis reaction of the first step may be performed at a temperature of 170 to 210°C, preferably 180 to 200°C for 5 to 9 hours, preferably 6 to 8 hours.

In addition, the first intermediate prepared in the first step may be a micro-carbon sphere, and the micro-carbon sphere may have an average size of 1 μm or less.

In addition, the first intermediate prepared in the first step may be used after being prepared, washed, and then freeze-dried.

Next, in the second step of the method for preparing the transition metal water decomposition catalyst of the present invention, a Ni ²⁺ precursor, a Co ²⁺ precursor, and urea are mixed with the first intermediate prepared in the first step, and a hydrothermal synthesis reaction (Hydrothermal synthesis process) can be carried out to prepare a second intermediate (indicated by Ni-Co-OH@CSs in FIG. 1).

At this time, the hydrothermal synthesis reaction of the second step may be performed at a temperature of 100 to 140°C, preferably 110 to 130°C for 4 to 8 hours, preferably 5 to 7 hours.

In addition, the second step may be mixed with respect to 100 parts by weight of the first intermediate, Ni ²⁺ precursor 225-275 parts by weight, preferably 237-263 parts by weight, and more preferably 255 parts by weight of ~ 245.

In addition, the second step may be mixed with respect to 100 parts by weight of the first intermediate, Co ²⁺ precursor 450-1050 parts by weight, preferably 675-825 parts by weight, and more preferably 788 parts by weight of ~ 712.

In addition, the second step may be mixed in an amount of 675 to 825 parts by weight, preferably 712 to 788 parts by weight, and more preferably 735 to 765 parts by weight, based on 100 parts by weight of the first intermediate.

In addition, the Ni ²⁺ precursor of the second step may include nickel nitrate (Ni(NO ₃ ) ₂ ), preferably nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O). have.

In addition, the Co ²⁺ precursor of the second step may include cobalt nitrate (Co(NO ₃ ) ₂ ), and preferably cobalt nitrate hexahydrate (Co(NO ₃ ) ₂ ·6H ₂ O). have.

In addition, the second intermediate prepared in the second step may be a micro carbon sphere in which nickel-cobalt-hydroxide (Ni-Co-OH) nanoneedles are formed in a direction perpendicular to the surface.

Next, in the third step of the method for preparing the transition metal water decomposition catalyst of the present invention, the second intermediate prepared in the second step undergoes an oxidation reaction, and the third intermediate (indicated as Ni-Co-O@CSs in FIG. 1) ) Can be manufactured.

The oxidation reaction is carried out under an argon (Ar) atmosphere, at a rate of 2 to 4°C/min, preferably 2.5 to 3.5°C/min, at a temperature of 260 to 340°C, preferably 280 to 320°C, for 2 to 4 hours, preferably It can be done for 2.5 to 3.5 hours.

In addition, the third intermediate prepared in the third step may be a micro carbon sphere in which nickel-cobalt-oxide (Ni-Co-O) nanoneedles are formed in a direction perpendicular to the surface.

Finally, the fourth step of the manufacturing method of the transition metal water decomposition catalyst of the invention is sodium hypophosphite to the third intermediate prepared in Step 3 (NaH ₂ PO _2), preferably sodium hypophosphite monohydrate (NaH ₂ PO ₂ · H ₂ O) can be mixed and substituted to prepare a transition metal phosphide water decomposition catalyst (indicated by Ni-Co-P@CSs in FIG. 1).

The substitution reaction is carried out under an argon (Ar) atmosphere, at a rate of 2 to 4°C/min, preferably 2.5 to 3.5°C/min, at a temperature of 260 to 340°C, preferably 280 to 320°C, for 2 to 4 hours, preferably It can be done for 2.5 to 3.5 hours.

In addition, the transition metal phosphide water decomposition catalyst prepared in the fourth step has a BET (Brunauer-Emmett-Teller) specific surface area ^{of 50 to 70 m 2} g ^{-1 , preferably 55 to 65 m 2} g ^-1 of BET (Brunauer -Emmett-Teller) can have a specific surface area.

In addition, the transition metal phosphide water decomposition catalyst prepared in step 4 may be a micro carbon sphere in which nickel-cobalt-phosphide (Ni-Co-P) nanoneedles are formed in a direction perpendicular to the surface, and the nickel-cobalt- The phosphide (Ni-Co-P) nanoneedle may be porous, and the nickel-cobalt-phosphide (Ni-Co-P) nanoneedle may have an average diameter of 30 to 70 nm, preferably 40 to 60 nm.

Meanwhile, the transition metal phosphide water decomposition catalyst of the present invention is a micro-carbon sphere and a porous nickel-cobalt-phosphide (Ni-Co-P) nanoneedle formed in a vertical direction on the surface of the micro-carbon sphere. It may include.

In this case, the micro carbon sphere may have an average size of 1 μm or less, and the porous nickel-cobalt-phosphide nanoneedle may have an average diameter of 30 to 70 nm, preferably 35 to 65 nm.

In addition, the transition metal phosphide water decomposition catalyst of the present invention has a BET (Brunauer-Emmett-Teller) specific surface area ^{of 50 to 70 m 2} g ^{-1 , preferably 55 to 65 m 2} g ^-1 of BET (Brunauer-Emmett- Teller) can have a specific surface area.

In addition, the transition metal phosphide water decomposition catalyst of the present invention is nickel (Ni) 8.05 to 10.05 mol%, preferably 8.55 to 9.55 mol%, cobalt (Co) 25.91 to 27.91 mol%, preferably based on the total mol% 26.41 to 26.41 mol%, phosphorus (P) 25.66 to 27.66 mol%, preferably 26.16 to 27.16 mol%, oxygen (O) 23.86 to 25.86 mol%, preferably 24.36 to 25.36 mol%, and carbon (C) 11.52 to 27.66 mol% It may contain 13.52 mol%, preferably 12.02 to 13.02 mol%.

The embodiments of the present invention have been described above, but these are only examples, and do not limit the embodiments of the present invention, and those of ordinary skill in the field to which the embodiments of the present invention belong to are not limited to the essential characteristics of the present invention. It will be appreciated that various modifications and applications not illustrated above are possible within the range not departing from. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Example 1: Preparation of a transition metal phosphide water decomposition catalyst (=see Fig. 1)

(1) Into a hydrothermal synthesizer, an autoclave (= Teflon-lined autoclave), a first aqueous solution (= _{an aqueous solution obtained by dissolving 8.0 g of glucose (C 6} H ₁₂ O ₆ ) in 60 ml of deionized water) was added, and then at 190°C. A first intermediate (=indicated by CS in FIG. 1) was prepared by performing a hydrothermal synthesis process at a temperature for 7 hours. The prepared first intermediate was washed three times with deionized water and ethanol, and then freeze-dried for 10 hours.

(2) 0.2 g of the freeze-dried first intermediate was added to 60 ml of deionized water, and ultrasonically treated for 30 minutes to uniformly disperse the first intermediate in deionized water. Under magnetic stirring (=magnetic stirring) nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O) 0.5 g, cobalt nitrate hexahydrate (Co(NO ₃ ) ₂ ·6H ₂ O) 1.5 g, urea 1.5 g was dissolved in deionized water in which the first intermediate was uniformly dispersed, and stirred for 30 minutes to prepare a second aqueous solution.

(3) Put the prepared second aqueous solution into a hydrothermal synthesizer, an autoclave (= Teflon-lined autoclave), and proceed with a hydrothermal synthesis process at a temperature of 120° C. for 6 hours to proceed with the second intermediate (= Fig. 1 of Ni-Co-OH@CSs) was prepared. The prepared second intermediate was washed three times with deionized water and ethanol, and then freeze-dried for 10 hours.

(4) The lyophilized second intermediate was oxidized to prepare a third intermediate (=indicated by Ni-Co-O@CSs in FIG. 1). Specifically, 1.0 g of the freeze-dried second intermediate was added to the freeze-dried second intermediate into a quartz tube of a quenching system, and in an argon (Ar) atmosphere, a rate of 3° C./min, The oxidation reaction was carried out at a temperature of 300° C. for 3 hours to prepare a third intermediate.

(5) The prepared third intermediate was substituted to prepare a transition metal phosphide water decomposition catalyst (=indicated by Ni-Co-P@CSs in FIG. 1). _{Specifically, an additional 5.0 g of sodium hypophosphite hydrate (NaH 2} PO ₂ ·H ₂ O) was additionally added to the quartz tube containing the third intermediate, and in an argon (Ar) atmosphere, a rate of 3° C./min, The substitution reaction was carried out at a temperature of 300° C. for 3 hours to prepare a transition metal phosphide water decomposition catalyst.

Example 2: Preparation of transition metal phosphide water decomposition catalyst

A catalyst for water decomposition of a transition metal phosphide was prepared in the same manner as in Example 1. However, unlike in Example 1, _{1.0 g of cobalt nitrate hexahydrate (Co(NO 3} ) ₂ ·6H ₂ O) was used to prepare a transition metal phosphide water decomposition catalyst.

Example 3: Preparation of transition metal phosphide water decomposition catalyst

A catalyst for water decomposition of a transition metal phosphide was prepared in the same manner as in Example 1. However, unlike Example 1, a transition metal phosphide water decomposition catalyst was prepared using 2.0 g of cobalt nitrate hexahydrate (Co(NO ₃ ) ₂ ·6H _{2 O).}

Comparative Example 1: Preparation of a transition metal phosphide water decomposition catalyst

(1) Into a hydrothermal synthesizer, an autoclave (= Teflon-lined autoclave), a first aqueous solution (= _{an aqueous solution obtained by dissolving 8.0 g of glucose (C 6} H ₁₂ O ₆ ) in 60 ml of deionized water) was added, and then at 190°C. A first intermediate was prepared by performing a hydrothermal synthesis process at a temperature for 7 hours. The prepared first intermediate was washed three times with deionized water and ethanol, and then freeze-dried for 10 hours.

(2) 0.2 g of the freeze-dried first intermediate was added to 60 ml of deionized water, and ultrasonically treated for 30 minutes to uniformly disperse the first intermediate in deionized water. Under magnetic stirring, 0.5 g of nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O) and 1.5 g of urea were dissolved in deionized water in which the first intermediate was uniformly dispersed, and 30 minutes While stirring to prepare a second aqueous solution.

(3) The prepared second aqueous solution was put into a hydrothermal synthesizer, an autoclave (= Teflon-lined autoclave), and a hydrothermal synthesis process was performed at a temperature of 120° C. for 6 hours to prepare a second intermediate. . The prepared second intermediate was washed three times with deionized water and ethanol, and then freeze-dried for 10 hours.

(4) The lyophilized second intermediate was oxidized to prepare a third intermediate. Specifically, 1.0 g of the freeze-dried second intermediate was added to the freeze-dried second intermediate into a quartz tube of a quenching system, and in an argon (Ar) atmosphere, a rate of 3° C./min, The oxidation reaction was carried out at a temperature of 300° C. for 3 hours to prepare a third intermediate.

(5) The prepared third intermediate was substituted to prepare a transition metal phosphide water decomposition catalyst (=indicated by Ni-Co-P@CSs in FIG. 1). _{Specifically, an additional 5.0 g of sodium hypophosphite hydrate (NaH 2} PO ₂ ·H ₂ O) was additionally added to the quartz tube containing the third intermediate, and in an argon (Ar) atmosphere, a rate of 3° C./min, The substitution reaction was performed at 300° C. for 3 hours to prepare a transition metal phosphide water decomposition catalyst.

Comparative Example 2: Preparation of a transition metal phosphide water decomposition catalyst

(1) Into a hydrothermal synthesizer, an autoclave (= Teflon-lined autoclave), a first aqueous solution (= _{an aqueous solution obtained by dissolving 8.0 g of glucose (C 6} H ₁₂ O ₆ ) in 60 ml of deionized water) was added, and then at 190°C. A first intermediate was prepared by performing a hydrothermal synthesis process at a temperature for 7 hours. The prepared first intermediate was washed three times with deionized water and ethanol, and then freeze-dried for 10 hours.

(2) 0.2 g of the freeze-dried first intermediate was added to 60 ml of deionized water, and ultrasonically treated for 30 minutes to uniformly disperse the first intermediate in deionized water. Under magnetic stirring, 1.5 g of cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O) and 1.5 g of urea are dissolved in deionized water in which the first intermediate is uniformly dispersed, and 30 minutes While stirring to prepare a second aqueous solution.

(3) The prepared second aqueous solution was put into a hydrothermal synthesizer, an autoclave (= Teflon-lined autoclave), and a hydrothermal synthesis process was performed at a temperature of 120° C. for 6 hours to prepare a second intermediate. . The prepared second intermediate was washed three times with deionized water and ethanol, and then freeze-dried for 10 hours.

(4) The lyophilized second intermediate was oxidized to prepare a third intermediate. Specifically, 1.0 g of the freeze-dried second intermediate was added to the freeze-dried second intermediate into a quartz tube of a quenching system, and in an argon (Ar) atmosphere, a rate of 3° C./min, The oxidation reaction was performed at a temperature of 300° C. for 3 hours to prepare a third intermediate.

(5) The prepared third intermediate was substituted to prepare a transition metal phosphide water decomposition catalyst (=indicated by Ni-Co-P@CSs in FIG. 1). _{Specifically, an additional 5.0 g of sodium hypophosphite hydrate (NaH 2} PO ₂ ·H ₂ O) was additionally added to the quartz tube containing the third intermediate, and in an argon (Ar) atmosphere, a rate of 3° C./min, The substitution reaction was carried out at a temperature of 300° C. for 3 hours to prepare a transition metal phosphide water decomposition catalyst.

Experimental Example 1: Surface structure analysis 1

For surface structure analysis, each of the first intermediate, second intermediate, and transition metal phosphide water decomposition catalyst prepared in Example 1 was analyzed using a field-emission scanning electron microscopy (FE-SEM). . As an analysis equipment, Supra 40 VP equipment (Zeiss Co., Germany) was used.

2(b) is an FE-SEM image of the first intermediate prepared in Example 1 measured at a magnification of 1 μm. As can be seen in FIG. 2(b), the first intermediate has a spherical shape and has an average size. Was confirmed to be a micro-carbon sphere of 1 μm or less.

2(c) to (d) are FE-SEM images of the second intermediate prepared in Example 1 measured at each magnification. As can be seen in FIGS. 2(c) and (d), the second intermediate Was confirmed that nickel-cobalt-hydroxide (Ni-Co-OH) was grown in a vertical direction on the surface of the first intermediate to have a nanoneedle structure. In addition, it was confirmed that the second intermediate had a diameter of 50 nm.

2 (e) to (g) are FE-SEM images of the transition metal phosphide water decomposition catalyst prepared in Example 1 measured at respective magnifications, as can be seen in (e) to (g) of FIG. 2 It was confirmed that the transition metal phosphide water decomposition catalyst prepared in Example 1 had a structure similar to that of the second intermediate. Specifically, the transition metal phosphide water decomposition catalyst is a nickel-cobalt-phosphide with a similar structure of nickel-cobalt-hydroxide (Ni-Co-OH) having a nanoneedle structure by growing in a vertical direction on the surface of the first intermediate. It was manufactured by being substituted with (Ni-Co-P), and the diameter was similar to that of the second intermediate, but it was confirmed that the surface was relatively rough and had porosity.

Experimental Example 2: Surface structure analysis 2

For surface structure analysis, the transition metal phosphide water decomposition catalyst prepared in Example 1 was analyzed using a transmission electron microscopy (TEM) and a high resolution transmission electron microscopy (HR-TEM). .

3A and 3B are TEM images of the transition metal phosphide water decomposition catalyst prepared in Example 1 measured at respective magnifications. Referring to FIGS. 3A and 3B, Example 1 It can be seen that the nanoneedles of the transition metal phosphide water decomposition catalyst prepared in have a hierarchical structure, and with reference to SAED (selected area electron diffraction) of FIG. 3(b), Example 1 It was confirmed that the transition metal phosphide water decomposition catalyst prepared in was multi-crystalline.

In addition, Figures 3 (c) to (e) are HR-TEM images measured at each magnification of the transition metal phosphide water decomposition catalyst prepared in Example 1. Referring to Figure 3 (c), Examples In the transition metal phosphide water decomposition catalyst prepared in 1, a number of nanoneedles of 5 nm or less were formed, so that the average diameter of the nanoneedles was about 50 nm,

In addition, referring to (c) of FIG. 3, it was confirmed that the nanoneedle is a porous architecture.

In addition, referring to (c) of FIG. 3, it can be seen that the crystalline state of the nanoneedle is surrounded by an amorphous phosphate layer.

In addition, referring to Figures 3 (d) to (e), the nanoneedles of the transition metal phosphide water decomposition catalyst prepared in Example 1 are nickel-phosphide (d-spacing) (d(1 1 1) ~0.22nm), as well as specific lattice fringes related to the interplanar distance (as d(1 1 1)∼0.247 nm, d(0 0 2)∼0.279 nm) of the cobalt-phosphide crystal phase. I was able to confirm that.

Experimental Example 3: Surface structure analysis 3

In order to check the dispersion state of the elements in the nanoneedle of the transition metal phosphide water decomposition catalyst prepared in Example 1, a scanning transmission electron microscopy (HAADF-STEM) equipped with an energy dispersion spectrometer (EDS) was used. The analysis was carried out.

3(f) to (j) show elemental mapping of the nanoneedle of the transition metal water decomposition catalyst prepared in Example 1 through an energy dispersion spectrometer (EDS), and (k) is As an EDAX spectrum that quantitatively analyzed this, referring to (f) to (j) of Fig. 3, nickel (Ni) and cobalt (Co) elements are concentrated in a part of the nanoneedle, and oxygen (O) and phosphorus (P) It was confirmed that the elements were homogeneously distributed in the nanoneedle.

In addition, referring to (k) of FIG. 3, elements constituting the transition metal water decomposition catalyst prepared in Example 1 are 9.05 mol% of nickel (Ni), 26.91 mol% of cobalt (Co), and 26.91 mol% of phosphorus with respect to the total mol% P) It was confirmed that it was composed of 26.66 mol%, oxygen (O) 24.86 mol%, and carbon (C) 12.52 mol%.

Experimental Example 4: Crystal structure analysis (X-ray diffraction pattern measurement)

The transition metal phosphide water decomposition catalyst prepared in Example 1 (=indicated by Ni ₁ Co ₃ -P@CSs in Fig. 4 (a) and (b)), the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 ( =The transition metal phosphide water decomposition catalyst prepared in (a) and (b) of Fig. 4) and the transition metal phosphide prepared in Comparative Example 2 (= Co-P@ in Fig. 4 (a) and (b)) Indicated by CSs) X-ray diffraction patterns (XRD) of each powder were measured, and the XRD patterns are shown in FIGS. 4A and 4B. At this time, the XRD pattern is 2θ(theta) = 5° to 85°, Cu target (λ = 0.154nm), and D/Max 2500V/PC (Rigaku Co., Japan) with a scan speed of ^{2°min -1} It was measured.

Experimental Example 5: XPS analysis

Using Theta Probe equipment (Thermo Fisher Scientific Inc., USA), the transition metal phosphide water decomposition catalyst prepared in Example 1 (=indicated as Ni ₁ Co ₃ -P@CSs in FIG. 4 (c)), performed The second intermediate prepared in Example 1 (=indicated by Ni ₁ Co ₃ -OH@CSs in FIG. 4 (c)), the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 (= in (c) of FIG. 4 Ni-P@CSs) and the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2 (=indicated as Co-P@CSs in Fig. 4(c)) each XPS (X-ray Photoelectron Spectroscopy) analysis And the results are shown in (c) to (f) of FIG. 4.

4C, the transition metal phosphide water decomposition catalyst prepared in Example 1, the second intermediate prepared in Example 1, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1, and Comparative Example 2 The prepared transition metal phosphide water decomposition catalyst had a small binding energy peak at 283.8 eV, which was confirmed to represent the C1s binding energy of the graphitic carbon structure of the first intermediate.

In addition, the transition metal phosphide water decomposition catalyst prepared in Example 1, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1, and the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2 showed a P2p binding energy peak at 132.4 eV. It was confirmed that the oxide was successfully substituted with a phosphide in the manufacturing process.

In addition, (d) of Figure 4 is a high-resolution XPS spectrum of the transition metal phosphide water decomposition catalyst Ni2p prepared in Example 1, 862.2 eV and 880.5 eV corresponding to Ni2p _3/2 and Ni2p _1/2 It was confirmed that a peak was observed at. In addition, it was confirmed that the doublet of 853.8 eV and 871.0 eV corresponds to Ni-P, and the doublet of 857.5 eV and 875.3 eV corresponds to Ni-phosphate.

In addition, (e) of FIG. 4 is a high-resolution XPS spectrum of the transition metal phosphide water decomposition catalyst Co2p prepared in Example 1, showing that peaks were observed at 779.1 eV and 793.9 eV as a result of the formation of Co-P. I could confirm. In addition, it was confirmed that the peaks observed at 782.4 eV and 798.3 eV originated from the oxidized state of Co from Co-phosphate. In addition, it was confirmed that peaks were observed at 786.0 eV and 803.1 eV corresponding to _{Co2p 3/2} and Co2p _1/2.

In addition, Figure 4 (f) is a high-resolution XPS spectrum of the transition metal phosphide water decomposition catalyst P2p prepared in Example 1 _{, corresponding to the P2p 3/2} and P2p _1/2 binding energy of the PP bond. It was confirmed that a doublet was observed at 129.2 eV and 130.1 eV. In addition, it was confirmed that a peak was observed at 133.5 eV corresponding to phosphate species.

Experimental Example 6: BET specific surface area analysis

The transition metal phosphide water decomposition catalyst prepared in Example 1 (=indicated by Ni ₁ Co ₃ -P@CSs in FIG. 5 (a)), the second intermediate prepared in Example 1 (= FIG. 5 (a)) In Ni ₁ Co ₃ -OH@CSs), the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 (=indicated as Ni-P@CSs in FIG. 5 (a)) and the transition prepared in Comparative Example 2 The adsorption-desorption isotherms of nitrogen of each of the metal phosphide water decomposition catalysts (=indicated by Co-P@CSs in FIG. 5(a)) are shown in FIG. 5(a). The specific surface area was investigated using the Brunauer-Emmett-Teller (BET) equation.

Through this, looking at the calculated BET (Brunauer-Emmett-Teller) specific surface area, the transition metal phosphide water decomposition catalyst prepared in Example 1 was 60 m ² g ^-1 , and the second intermediate prepared in Example 1 was 50 m. ² g ^-1, the transition metal phosphide with water and decomposing catalyst prepared in Comparative example 1 was 36 m ² g ^-1, the transition metal phosphide water decomposition catalyst prepared in Comparative example 2 was confirmed to be 38 m ² g ^-1.

In addition, Figure 5 (b) is a transition metal phosphide water decomposition catalyst prepared in Example 1 (= represented by Ni ₁ Co ₃ -P@CSs in Figure 5 (a)), the second prepared in Example 1 Intermediate (= represented by Ni ₁ Co ₃ -OH@CSs in FIG. 5 (a)), the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 (= represented by Ni-P@CSs in FIG. 5 (a)) ) And the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2 (=indicated by Co-P@CSs in FIG. 5(a)), respectively, the pore volume based on the Barrett-Joyner-Halenda (BJH) method ) Versus pore size distribution curve. Referring to (b) of Figure 5, the pore size of each material is distributed in the range of 4 ~ 9nm, it can be confirmed that it has a mesoporous nature, in particular, the transition metal prepared in Example 1 It was confirmed that the pore volume of the phosphide water decomposition catalyst was significantly higher than that of other materials.

The following electrocatalytic activity measurement was performed using a CH660D workstation (CH Instruments Inc., USA) integrated into a three-electrode system. In addition, a rotating disk electrode (RDE, diameter: 0.071 cm ² ) containing catalyst powder, graphite rod and Ag/AgCl is used as a working electrode, counter electrode, and reference electrode, respectively. I did.

Experimental Example 7: Measurement of electrocatalytic activity 1

10% by weight of platinum-mixed carbon (= represented by Pt/C in Fig. 6 (a) to (f)), the transition metal phosphide water decomposition catalyst prepared in Example 1 (= Fig. 6 (a) ~ (f) in Ni ₁ Co ₃ -P@CSs), the transition metal phosphide water decomposition catalyst prepared in Example 2 (= from (a) to (f) of FIG. 6 to Ni ₁ Co ₂ -P@CSs Indication), the transition metal phosphide water decomposition catalyst prepared in Example 3 (=indicated by Ni ₁ Co ₄ -P@CSs in (a) to (f) of FIG. 6), the second intermediate prepared in Example 1 ( _{= Ni 1} Co ₃ -OH@CSs in Fig. 6 (a) ~ (f)), the third intermediate prepared in Example 1 (= Ni ₁ Co _{3 in Fig. 6 (a) ~ (f)} -O@CSs), the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 (=indicated as Ni-P@CSs in (a) to (f) of FIG. 6) and the transition metal prepared in Comparative Example 2 Hydrogen evolution reaction (HER; hydrogen evolution reaction) performance of each of the phosphide water decomposition catalysts (=indicated by Co-P@CSs in FIGS. 6A to 6F) was measured.

6A to 6C are graphs measuring a linear sweep voltammetry (LSV) in a scan rate ^{of 10 mVs -1 and 0.1M KOH electrolyte, and FIGS. 6A to 6C} ), it can be seen that the transition metal phosphide water decomposition catalyst prepared in Example 1 requires an overpotential (η) of 57 mV to generate a cathode current density ^{of 10 mAcm -2,} It was confirmed that the lowest overvoltage was required than other materials. In addition, it can be seen that the transition metal phosphide water decomposition catalyst prepared in Example 1 ^{generates a cathode current density of 140 mAcm -2} at an overpotential (η) of 500 mV, and thus a hydrogen evolution reaction (HER) It was confirmed that the performance was excellent.

In addition, Figure 6 (d) is a graph showing the Tafel slopes, the carbon mixed with 10% by weight of platinum is 33 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Example 1 is 44 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Example 2 is 50 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Example 3 is 48 mVdec ^-1 , the second intermediate prepared in Example 1 is 170 mVdec ^-1 , the third intermediate prepared in Example 1 is 128 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 is 119 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2 is It was confirmed that it had a value of 133 mVdec ^-1.

In addition, Figure 6 (e) is a graph measuring the capacitive current density (capacitive J) at a scan rate of 0.86 ~ 0.96 V potential range, 2 ~ 25 mVs ^{-1, prepared in Example 1.} It was confirmed that the electrochemically active surface area (ECAS) value of the transition metal phosphide water decomposition catalyst was significantly superior to that of other materials.

In addition, Figure 6 (f) is a graph measuring the chronoamperometric stability of the transition metal phosphide water decomposition catalyst prepared in Example 1 at current densities ^{of 10mAcm -2} and 100mAcm ^{-2 , 10mAcm -2} At the current density of, it was confirmed that it had excellent durability without a decrease in the current density for a long time, and at the current density of 10mAcm ^-2 , it was confirmed that 6% deflection occurred after 30 hours.

Experimental Example 8: Measurement of electrocatalytic activity 2

10% by weight of ruthenium oxide (RuO _{2 ) mixed carbon (=indicated by PuO 2} /C in Fig. 7 (a) to (f)), the transition metal phosphide water decomposition catalyst prepared in Example 1 (= FIG. In (a) to (f) of 7 Ni ₁ Co ₃ -P@CSs), the transition metal phosphide water decomposition catalyst prepared in Example 2 (= Ni ₁ Co in (a) to (f) of FIG. 7 ₂ -P@CSs), the transition metal phosphide water decomposition catalyst prepared in Example 3 (=indicated as Ni ₁ Co ₄ -P@CSs in Figure 7 (a) to (f)), in Example 1 _{The prepared second intermediate (= represented by Ni 1} Co ₃ -OH@CSs in Fig. 6 (a) to (f)), the third intermediate prepared in Example 1 (= Fig. 6 (a) to (f) ) In Ni ₁ Co ₃ -O@CSs), the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 (=indicated as Ni-P@CSs in (a) to (f) of FIG. 6) and Comparative Example The oxygen evolution reaction (OER; Oxygen Evolution Reaction) performance of each of the transition metal phosphide water decomposition catalysts prepared in 2 (=indicated by Co-P@CSs in Fig. 6 (a) to (f)) was measured.

7A to 7C are graphs measuring a linear sweep voltammetry (LSV) in a 0.1M KOH electrolyte saturated with nitrogen gas and a scan rate ^{of 10 mVs -1.} Referring to a) to (c), the transition metal phosphide water decomposition catalyst prepared in Example 1 requires an overpotential (η) of 330 mV to generate a cathodic current density ^{of 20 mAcm -2.} As can be confirmed, it was confirmed that the lowest overvoltage was required than other materials. In addition, it can be seen that the transition metal phosphide water decomposition catalyst prepared in Example 1 ^{generates a cathode current density of 58.6mAcm -2} at an overpotential (η) of 500 mV, and thus an oxygen evolution reaction (OER; Oxygen Evolution Reaction Reaction). ) It was confirmed that the performance was excellent.

In addition, Figure 7 (d) is a graph showing the Tafel slopes, in which 10% by weight of ruthenium oxide (RuO ₂ ) is mixed carbon is 277 mVdec ^-1 , the transition metal phosphide prepared in Example 1 The decomposition catalyst was 113 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Example 2 was 153 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Example 3 was 178 mVdec ^-1 , The second intermediate was 210 mVdec ^-1 , the third intermediate prepared in Example 1 was 231 mVdec ^-1 , the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 was 246 mVdec ^-1 , and the transition metal prepared in Comparative Example 2 It was confirmed that the phosphide water decomposition catalyst had a ^{value of 231 mVdec -1.}

Figure 7 (e) is a graph measuring electrochemical impedance (EIS) when applying a potential of -0.4V in the frequency range ^{of 10 5} ~ 10 ^{-2, the transition metal phosphide prepared in Example 1} The water decomposition catalyst is 65 Ω, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 1 is 109 Ω, the transition metal phosphide water decomposition catalyst prepared in Example 2 is 85 Ω, and the transition metal phosphide prepared in Example 3 is water decomposed. It was confirmed that the catalyst was 76 Ω, the transition metal phosphide water decomposition catalyst prepared in Comparative Example 2 was 84 Ω, and the third intermediate prepared in Example 1 had an Rct value of 110 Ω.

FIG. 7(f) shows a cathode current density of 10 mAcm in 1 cycling process and 1000 cycling process in order to confirm the stability of the transition metal phosphide water decomposition catalyst prepared in Example 1. ^{As a graph measuring the overpotential required to maintain -2} , it was confirmed that the 1 cycling process and the 1000 cycling process showed the same graph.

Experimental Example 9: Evaluation of suitability for use as a catalyst for water decomposition

As shown in (a) of FIG. 8, the transition metal phosphide water decomposition catalyst prepared in Example 1 was used as a negative electrode and a positive electrode, and an electrolyzer system of Preparation Example 1 was prepared using 0.1 M KOH as an electrolyte. In addition, in order to compare with the electrolyzer system of Preparation Example 1, the electrolytic cell system of Preparation Example 1 was prepared in the same manner as the electrolyzer system of Preparation Example 1, but the transition metal water decomposition catalyst prepared in Comparative Example 1 was used as the cathode, and the transition metal water decomposition catalyst prepared in Comparative Example 2 was used. An electrolytic cell system of Comparative Preparation Example 1 was prepared by using as a positive electrode and using 0.1M KOH as an electrolyte.

(B) of FIG. 8 is an electrolytic cell system of Preparation Example 1 (indicated by Ni ₁ Co ₃ -OH@CSs (+)/Ni ₁ Co ₃ -OH@CSs (-) in FIG. 8 (b)) and comparative manufacturing As a graph showing the linear sweep voltammetry (LSV) of each of the electrolyzer system of Example 1 (indicated by RuO ₂ /C(+)/PT/C(-) in FIG. 8(b)), Preparation Example 1 of the electrolytic cell is an electrolytic cell system, the system of the battery voltage, compare the production of 1.54V example 1 with respect to the overall water splitting at a current density of 50mAcm ^-2 is having a battery voltage of 1.58V with respect to the overall water splitting at a current density of 50mAcm ^-2 Was able to confirm. It can be confirmed that this has superior performance than the previously reported water decomposition catalyst, and specifically, as described in FIG. 8(c), each paper ([53], [54], in FIG. 8(c)) [55], [56], [57], [58], [59], [60], [61], [62], [15], [63] It was able to confirm the excellence.

(Articles denoted as [15]: J. Li, G. Zheng, One-dimensional earth-abundant nanomaterials for water-splitting electrocatalysts, Adv. Sci. 4 (2017), Papers denoted as [53]: Y. Zhang, Q. Shao, S. Long, X. Huang, Cobalt-molybdenum nanosheet arrays as highly efficient and stable earth-abundant electrocatalysts for overall water splitting, Nano Energy 45 (2018) 448-455, [54] Paper denoted by: N. Mahmood , Y. Yao, JW Zhang, L. Pan, X. Zhang, JJ Zou, Electrocatalysts for hydrogen evolution in alkaline electrolytes: mechanisms, challenges, and prospective solutions, Adv. Sci. 5 (2018) 1700464, denoted [55] Papers: C. Dong, X. Yuan, X. Wang, X. Liu, W. Dong, R. Wang, Rational design of cobalt-chromium layered double hydroxide as a highly efficient electrocatalyst for water oxidation, J. Mater. Chem. Paper denoted as A 4 (2016) 11292-11298, [56]: Y. Liu, AZ Fire, S. Boyd, RA Olshen, Mechanistic studies of the oxygen evolution reaction by a cobalt-phosphate catalyst at neutral pH, J. Am Chem. Soc. 132 (2010) 16501-16509, [57] Thesis: L.A. Stern, L. Feng, F. Song, X. Hu, Ni2P as a Janus catalyst for water splitting: The oxygen evolution activity of Ni2P nanoparticles, Energy Environ. Sci. Articles denoted as 8 (2015) 2347-2351, [58]: J. Ryu, N. Jung, J.H. Jang, H.J. Kim, S.J. Yoo, In situ transformation of hydrogenevolving CoP nanoparticles: Toward efficient oxygen evolution catalysts bearing dispersed morphologies with Co-oxo/hydroxo molecular units, ACS Catal. 5 (2015) 4066-4074, [59]: A. Dutta, N. Pradhan, Developments of metal phosphides as efficient OER precatalysts, J. Phys. Chem. Lett. Articles denoted as 8 (2017) 144-152, [60]: Y. Jia, L. Zhang, G. Gao, H. Chen, B. Wang, J. Zhou, M.T. Soo, A heterostructure coupling of exfoliated Ni-Fe hydroxide nanosheet and defective graphene as a bifunctional electrocatalyst for overall water splitting, Adv. Mater. Papers denoted 29 (2017) 1-8, [61]: M. Gong, W. Zhou, M. Tsai, J. Zhou, M. Guan, M. Lin, B. Zhang, Y. Hu, D. Wang , structures for active hydrogen evolution electrocatalysis, Nat. Commun. 5 (2014) 1-6, [62]: Y. Tan, H. Wang, P. Liu, Y. Shen, C. Cheng, Versatile nanoporous bimetallic phosphides towards electrochemical water splitting, Energy Environ. Sci. 9 (2016) 2257-2261, [63]: H. Wang, H. Lee, Y. Deng, Z. Lu, P. Hsu, Y. Liu, D. Lin, Y. Cui, Bifunctional nonnoble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting, Nat. Commun. 6 (2015) 1-8)

(D) of FIG. 8 is an electrolytic cell system of Preparation Example 1 (indicated by Ni ₁ Co ₃ -OH@CSs (+)/Ni ₁ Co ₃ -OH@CSs (-) in FIG. 8 (b)) and comparative manufacturing The electrolytic cell system of Example 1 (indicated by RuO ₂ /C(+)/PT/C(-) in FIG. 8(b)) during water-splitting at a current density of ^{50 mAcm -2} As a graph showing the stability, it was confirmed that the electrolyzer system of Preparation Example 1 has better stability than the electrolyzer system of Comparative Production Example 1 for a long water decomposition time (~ 38 hours).

(E) of FIG. 8 shows the electrolyzer system of Preparation Example 1 ^{undergoing water decomposition at a current density of 50 mAcm -2} for 38 hours, and then the transition metal phosphide water decomposition catalyst prepared in Example 1 used as a cathode and an anode. It is an FE-SEM image measured at a magnification of 200 nm, and (f) of FIG. 8 shows the electrolytic cell system of Preparation Example 1 after undergoing water decomposition for 38 hours at a current density of 50 ^{mAcm -2, and then used as a cathode and an anode.} The transition metal phosphide water decomposition catalyst prepared in Example 1 shows elemental mapping measured through an energy dispersive spectrometer (EDS), and referring to (e) to (f) of FIG. 8, in Example 1 It was confirmed that the prepared transition metal phosphide water decomposition catalyst maintained its appearance without any special change even after decomposing water for 38 hours.

The present invention relates to a transition metal phosphide water decomposition catalyst and a method for preparing the same, and more particularly, to a transition metal phosphide water decomposition catalyst having excellent water decomposition activity, and a method for preparing the same.

Claims (8)

A first step of preparing a first intermediate in an aqueous solution containing _{glucose (glucose, C 6} H ₁₂ O ₆ ) by proceeding a hydrothermal synthesis process; A second step of preparing a second intermediate by mixing a Ni ²⁺ precursor, a Co ²⁺ precursor, and urea with the first intermediate, and performing a hydrothermal synthesis process; A third step of producing a third intermediate by subjecting the second intermediate to an oxidation reaction; And A fourth step of mixing and replacing sodium hypophosphite (NaH ₂ PO ₂ ) with the third intermediate to prepare a transition metal phosphide water decomposition catalyst; A method for producing a transition metal phosphide water decomposition catalyst comprising a. The method of claim 1, The Ni ²⁺ precursor includes nickel nitrate (Ni(NO ₃ ) ₂ ), and the Co ²⁺ precursor includes cobalt nitrate (Co(NO ₃ ) ₂ ). Manufacturing method. The method of claim 1, The hydrothermal synthesis reaction of the first step proceeds for 5 to 9 hours at a temperature of 170 to 210°C, The hydrothermal synthesis reaction of the second step is a method for producing a catalyst for water decomposition of a transition metal phosphide, characterized in that for 4 to 8 hours at a temperature of 100 to 140°C. The method of claim 1, The second step is a method for producing a transition metal phosphide water decomposition catalyst, characterized in that mixing 225 to 275 parts by weight of a ^{Ni 2+ precursor and 450 to 1050 parts by weight of a Co 2+} precursor based on 100 parts by weight of the first intermediate. The method of claim 1, The oxidation reaction in the third step and the substitution reaction in the fourth step are respectively carried out under an argon (Ar) atmosphere at a rate of 2 to 4°C/min and a temperature of 260 to 340°C for 2 to 4 hours. Transition metal phosphide water decomposition catalyst manufacturing method The method of claim 1, The transition metal phosphide water decomposition catalyst has a BET (Brunauer-Emmett-Teller) specific surface area of ^{50 to 70 m 2} g ^-1. The method of claim 1, The first intermediate is a micro-carbon sphere having an average size of 1 μm or less, The second intermediate is a micro carbon sphere in which nickel-cobalt-hydroxide (Ni-Co-OH) nanoneedles are formed in a direction perpendicular to the surface, The third intermediate is a micro carbon sphere in which nickel-cobalt-oxide (Ni-Co-O) nanoneedles are formed in a direction perpendicular to the surface, The fourth intermediate is a transition metal phosphide water decomposition catalyst, characterized in that the fourth intermediate is a micro-carbon sphere formed with porous nickel-cobalt-phosphide (Ni-Co-P) nanoneedles having an average diameter of 30 to 70 nm in a direction perpendicular to the surface. Method of manufacturing. Micro-carbon sphere; And Porous nickel-cobalt-phosphide (Ni-Co-P) nanoneedles formed in a vertical direction on the surface of the micro carbon sphere; Including, Based on the total mole %, nickel (Ni) 8.05-10.05 mol%, cobalt (Co) 25.91 ~ 27.91 mol%, phosphorus (P) 25.66 ~ 27.66 mol%, oxygen (O) 23.86 ~ 25.86 mol% and carbon (C) A transition metal phosphide water decomposition catalyst comprising 11.52 to 13.52 mol%.

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